In the labeling of containers, there is risk that the wrong label will be applied to a container. In other words, there is risk that a container will be mislabeled. This can happen, for example, if the wrong labels are fed by mistake or negligence to the labeling machine.
This is an important problem for manufacturers of pharmaceuticals and it has become conventional in this field, and in other fields where mislabeling can be dangerous, to provide safeguards to minimize the possibility of mislabeling. In conventional practice, this is carried out by including on the label itself a bar code representing the contents denoted by the label, optically scanning the pattern of the bar code as the label is being applied and comparing the reading to that which should represent the contents of the container, and automatically stopping the labeler responsive to any difference.
However, because of copy requirements, label size and/or aesthetics, some labels cannot accommodate a bar code. Consideration has been given to this problem. Sallenbach U.S. Pat. No. 4,372,681 solves this problem by including the bar code on a separate strip mounted on the same side of the backing strip as the label. This is disadvantageous in that additional material is required for the separate strip. Coakley U.S. Pat. No. 2,551,364 discloses printing the code on a tab or extension of the label which is cut off or otherwise removed after the label passes the verifying device. Von Hofe U.S. Pat. No. 3,607,537 also depicts tab extensions of a label bearing verifying indicia. These require extra label material than would otherwise be used.